PCR by Johann van Blerck

PCR is revealed above by the shaft inserted into the new rudder tube.

For three years now I’ve been wondering if positive caster would improve the performance of a surfski on waves. Thinking it through countless times while sliding sideways on waves I couldn’t come up with any reason why it shouldn’t. Paddling on flat water I thought, might be its only drawback but in practice this hasn’t been the case. PCR has no advantage on flat water.

I recently damaged the tail of my Fenn Millenium and decided to build in my PCR (positive caster rudder) idea. I chose a fairly aggressive rudder post angle of 23 degrees as I wanted a definite change and also think the chosen angle is the best bang for buck. Less PC will give less downward force and more PC will give more downward force but less turning force. The implementation was simple enough and achieved simply by moving the lower rudder post hole 55mm further forward and leaving the top one in the deck well as stock.After the deck was remove for accident repairs a block of epoxy glass was bonded between the hull and deck after being suitably drilled. The rudder runs directly in this block.

The stock rudder was simply modified by grinding away and exposing more of the rudder shaft to penetrate the now longer rudder tube and the resultant new gap between the rudder and hull was built up with epoxy/glass and is easily seen in the picture. The current installation limits the steering angle in either direction to just 33 degrees and this has proved adequate on the water.

I’ve only been able to test PCR on ferry wakes for now but from the moment I got onto the first wake I knew I was onto something. The wakes I ride are regulars and I’m familiar with what it takes to stay on them with out spinning out (broaching?). They’re pretty easy to ride if you’re reasonably fit and don’t loose concentration because the spin out point of no return is a fine line between running parallel with the vessel and therefore proceeding in the same direction as the vessel and maintaining an acute angle to the wave. With PCR the fine line is gone, replaced with a broad range of control and feel. Maintaining speed with less paddle effort also seems to be the case with PCR and is possibly due to the fact that previously a large (high drag) rudder angle had to be used to maintain direction while PCR requires far less rudder angle to be effective.

To date I’ve not been able to do a decent downwind but have no doubt that the stunning performance on wake waves will translate into vastly improved downwind control and speed especially on technical down winds where waves have to be ridden at an angle where increased speed and control make a major difference.

How good is PCR? I’ll stick my neck out and say that soon, all open water racing ski’s will incorporate PCR and Molokai will be won with PCR, possibly by next year.

It's almost impossible to photograph PCR but here's a view looking forward with the rudder hard left.

The outline shows the original rudder outline and existing shaft.

Two holes are a simple epoxy crack stitch and the other holes just key the new build to the old.